1. Color blindness is rare in women but possible; when a woman is color blind ________. 1.her father will also be color blind 2.all of her sons will also be color blind 3.her mother will also be color blind 4.she will also suffer from Turner's syndrome 5.her genotype will be XXY 12345

2. The probability that a crossover will disrupt the linkage between two genes is proportional to the ________. 1.number of alleles for the genes 2.distance between the genes 3.diploid number for that species 4.time of expression of the genes 5.degree of pleiotropy displayed by the gene 12345

3. The incidence of Down syndrome increases ________. 1.when identical twins or triplets have been conceived 2.both parents are heterozygous for Down syndrome 3.if either of the parents is aneuploid 4.for families with Down syndrome in their pedigree 5.once the mother's age is greater than 35 12345

4. Normal human cells have 46 chromosomes; a monosomic cell will have ________ chromosome(s). 1.1 2.22 3.23 4.45 5.92 12345

5. Cri-du-chat syndrome is caused by a deletion on chromosome 5; deletions occur when ________. 1.a portion of a chromosome is relocated onto a second chromosome 2.homologous chromosomes fail to separate during meiosis 3.a portion from the end or within the middle is lost 4.a son inherits a defective X chromosome from his mother 5.a section of chromosome breaks free but is reconnected to its chromosome in reverse order 12345

6. Sickle-cell trait occurs in individuals heterozygous for the autosomal-recessive gene. What is the likelihood that a person who has two parents with sickle-cell trait will have the disorder? 1.100% (certain) 2.0% (impossible) 3.50% 4.25% 5.not enough information given to answer the question 12345

7. Genetic abnormalities can be diagnosed prenatally through ________. 1.chorionic villi sampling 2.fetoscopy 3.amniocentesis 4.an examination of fetal blood 5.all of the choices 12345

8. Neurobiological disorders (NBDs) such as schizophrenia ________. 12345 1.must be autosomal recessive since afflicted parents always have afflicted children 2.are clearly caused by genetic factors since both identical twins always either suffer the disease or do not 3.may have genetic susceptibilities but do not appear to be caused by a single gene. 4.appear to be caused by an autosomal-dominant gene 5.appear to have some sex linkage since men suffer NBDs more often than women

9. When X-chromosome nondisjunction occurs during mitosis in an embryo, the ________. 1.affected gamete results in aneuploidy after conception 2.percentage of affected sons will be greater than affected daughters 3.individual will be genetically male but phenotypically female 4.incidence of X-linked disorders will no longer show a gender bias 5.daughter cells will differ in chromosome number, resulting in a mosaic karyotype 12345

10. Couples who are at risk of passing on the allele for muscular dystrophy may utilize ________ to minimize the possibility. 1.preimplantation diagnosis 2.karyotyping to evaluate the gametes prior to in vitro fertilization 3.expansion mutation technology 4.phenotypic treatment 5.all of the choices 12345

11. The procedure that binds fluorescent dyes to prepared chromosomes is called ________. 12345 1.spectral karyotyping 2.disjunction 3.inversion technology 4.phenotypic treatment 5.restriction analysis

12. Two parents, both carriers for galactosemia, have a child that is phenotypically normal; what is the probability that the child is a carrier? 1.1 in 4 (25%) 2.1 in 2 (50%) 3.1 in 3 (33%) 4.2 in 3 (67%) 5.3 in 4 (75%) 12345

13. While conducting reciprocal crosses with fly eye color, Morgan observed that ________. 1.white-eyed males did not find red- eyed females sexually attractive 2.flies homozygous for white eyes did not survive to sexual maturity 3.the F1 ratios were dependent on the gender of the parent with white eyes 4.the white-eyed trait was lost to the population by the end of the F4 generation 5.the parental source of the allele, as with peas, did not influence the F1 ratios 12345

14. Huntington's disease has been shown to be caused by an expansion mutation, a condition occurring when ________. 1.a portion of one chromosome is inserted into another 2.a gene becomes elongated following the repetitive addition of small DNA segments called repeats 3.a section of DNA is moved from one homologous chromosome to the other, producing abnormally long and short chromosomes 4.homologous chromosomes fail to separate, and then join end to end 5.none of the choices describes expansion 12345

15. How does the presence of the Y chromosome direct the embryo to become male? 1.all the genes for the male phenotype are found on the Y chromosome 2.the amount of estrogen produced by XY cells is too small to activate the genes directing female development, causing the embryo to become male 3.the Y chromosome carries a gene for testes formation; the testes then produce testosterone, which activates genes on numerous chromosomes 4.the combination of X and Y gene products combine to form a receptor, which is sensitive to the hormones produced by the mother 5.biologists are uncertain, but the question addresses an area of active research 12345

16. If a man who is homozygous for an autosomal- dominant condition has children with a woman who does not carry genes for that condition, ________. 1.all of their offspring will inherit the condition, regardless of their gender 2.three-quarters of their offspring will inherit the condition 3.none of their offspring will inherit the condition, but half will be carriers 4.half of their offspring will inherit the condition 5.half of their sons will inherit the condition and half of their daughters will be carriers 12345

17. Comparisons of human and great ape chromosomes suggest that ________. 1.the two groups are, at best, distantly related and have been evolving separately for a long time 2.two ape chromosomes fused, reducing the human chromosome number to one pair less than the apes 3.chromosomal change is too disruptive to be a component in evolutionary change 4.selection always opposes chromosomal alteration, causing total number and structure to be highly conserved 5.any similarities are coincidental, as virtually no homologous regions exist between any pair of chromosomes 12345

18. Analysis of the pedigree for the descendants of King George III and Louis II suggests that ________. 1.Queen Victoria suffered from hemophilia 2.hemophilia is caused by a dominant allele carried on the X chromosome 3.Hemophilia was introduced to the European monarchy from sources from France 4.Queen Victoria was a carrier for hemophilia 5.males suffering from hemophilia always died early in life without leaving children 12345

19. Since dominant alleles are always expressed and detected, how can the persistence of autosomal- dominant disorders be explained? 1.many individuals with dominant disorders have overcome the challenges they present and have decided to have children 2.some dominant alleles are not expressed until after the age when most people have reproduced 3.unless the symptoms of the disorder prevent reproduction, the gene may be passed on 4.some conditions are continually reintroduced to a population through spontaneous mutation 5.all of the choices 12345

20. Down syndrome ________. 1.is observed only in females 2.is also known as trisomy 21 3.affects only the central nervous system 4.results from a deletion 5.is a Y-linked disorder, passed directly from father to son 12345